Sure, that is what I want to test: done with the command
testparm...I can now proceed with separate models

I'm unclear on the separate models part. Just because the effects of
x1-x5 are equal does not mean that you would run separate models, one
using only x1, one using only x2, etc. All 5 variables (or perhaps
an additive scale created from them) should probably still be in the
model. But again, I don't know what the x's are, nor do I know what
you are trying to accomplish. Perhaps you could describe your goals
in a bit more detail.